Multiple element zone of focus artificial hydrogel lens

ABSTRACT

An implantable or contact hydrogel lens for replacement of a defective natural lens in an eye in which various portions of the lens have different powers and focal lengths to produce in-focus images on the retina, of objects which are located at various distances from the eye, thereby substituting for the natural focusing action of the eye. The image processing capability of the brain functions to largely ignore the out-of-focus images and concentrate on the in-focus image of the object selected by the brain for consideration.

CROSS REFERENCE TO CO-PENDING APPLICATIONS

This application is a continuation-in-part of application Ser. No.07/088,412, filed Aug. 24, 1987, entitled "Multiple Element Zone ofFocus Artificial Lens", now U.S. Pat. No. 4,778,462; which is related inpart to application Ser. No. 07/258,028, filed Oct. 17, 1988, entitled"Laminated Zone of Focus Artificial Hydrogel Lens", which is acontinuation-in-part of application Ser. No. 07/088,428, filed Aug. 24,1987, entitled "Laminated Zone of Focus Artificial Lens", now U.S. pat.No. 4,798,609; application Ser. No. 07/258,027, filed Oct. 17, 1988,entitled "Cylindrical Segmented Zone of Focus Artificial Hydrogel Lens",which is a continuation-in-part of application Ser. No. 07/088,413,filed Aug. 24, 1987, entitled "Cylindrically Segmented Zone of FocusArtificial Lens", now U.S. Pat. No. 4,795,462; and application Ser. No.07/258,029, filed Oct. 17, 1988, entitled "Radially Segmented Zone ofFocus Artificial Hydrogel Lens", which is a continuation-in-part ofapplication Ser. No. 07/088,249, filed Aug. 24, 1987entitled "RadiallySegmented Zone of Focus Artificial Lens", now U.S. Pat. No. 4,798,609.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to an implantable intraocular lens, andmore particularly, pertains to a hydrogel lens containing multiple lenselements.

This invention relates to hydrogel lenses which have areas which serveto bring impinging rays to a focus in specific areas of the focal plane.Such lenses are called zone of focus lenses and are particularly usefulfor implantation into the eye as a substitute for the natural lenssince, in combination with the brain, they effectively replicate theability of the natural lens to bring objects at varying distances to asharp focus.

The invention relates specifically to a zone of focus lens in which thehydrogel lens is made up of discrete lens elements distributed over thesurface of the lens. Each element serves to bring the impinging raysfrom an object at a predetermined distance to a focus on a particularregion of the retina. By selecting various powers for the hydrogel lenselements, it is possible to have an object at a given distance broughtto an acceptable focus by at least one of such elements. In this manner,an in-focus image (sharp image) is created on a particular portion ofthe retina serviced by that element. It has been found that theprocessing of the image by the brain results in the selectiveconsideration of the sharpest image and the virtual discard of the otherout-of-focus images created by other elements.

2. Description of the Prior Art

Limited attempts have been made to produce a lens having areas ofvarying powers. There have been many attempts to produce implantablelenses which serve for both close and far seeing, similar to the bifocalspectacles. In general, such lenses have been produced from the rigidmaterials with two regions having different powers. The light whichimpinges on the retina passes through one region to the exclusion of theother. In such a system, only one region of the lens is used at a time,and there is no accommodation by the brain to reject an out-of-focusimage. Great care and accuracy must be used in the preoperativemeasurements since both the near and far powers must be accuratelydetermined. Since the near and far powers are not specificallyinterrelated, the inventory requirements are compounded since a varietyof near powers must be available for every far power.

Such lenses will allow placement through a small incision forimplantation. The post-operative recovery period is shorter when a tinyincision is made.

SUMMARY OF THE INVENTION

The lens is a composite of individual hydrogel lens elements, each ofwhich has a distinct power and focal length. Each element brings theimpinging rays to bear on a predetermined portion of the retina, whichmay be either unique to that element or shared with other elements oflike power. The hydrogel elements are selected to have a sufficientrange of powers to accommodate the projected use. That is, the value ofthe power and the number of elements will be determined by the projecteduse. Most uses can be accommodated with a lens having two or threepowers to accommodate objects at near, far and intermediate distances.These powers can be distributed among a like number of elements or anumber of elements which is two, three or even more times the number ofpowers. The distribution of powers among the elements need not be doneequally. For example, if most of the sight is required at closedistances, the number of elements for this distance can be increased andthe number of elements for far vision correspondingly decreased.

Accommodation of the brain to such an arrangement may be enhanced byadding a distinctive color to the elements of like power. This approachmay be utilized where loss or impairment of color vision is of littleconsequence.

Hydrogel lens elements of differing powers can be provided by molding,grinding, lathe cutting or otherwise forming individual lens elementsfrom hydrogel materials having different indices of refraction andmounting them in an assembly to form a unitary lens structure.

In the alternative, the individual lens elements can be fabricated oflike hydrogel material and the differing powers obtained by grinding,molding or otherwise shaping the surface of the individual lens elementsto provide individual curvatures.

Lens is a generic term for intraocular lens, intracorneal lens, orcontact lens. Lenses also include any optical lens such as for a camera,television, telescopes, projectors, optical instruments, glasses, etc.

It is a principal object hereof to provide a hydrogel lens incorporatinga multiple element zone of focus.

It is therefore an object of this invention to provide a zone of focushydrogel lens which will make the replacement of a defective naturallens available to many who cannot now afford the operation.

It is another object of the invention to provide a zone of focushydrogel lens which does not require either an extensive inventory ofvarious powers and combination of powers or extensive preoperativemeasurement prior to implantation into the eye as a replacement for adefective lens.

Still another object of this invention is to provide an approach to thereplacement of a defective lens by providing a very nearly universalhydrogel lens which provides vision adequate to allow a normal lifestyle.

These lenses can be used as replacements for the presbyoptic lens of theaging population and thereby allowing for both near and distant visionwithout the use of spectacles. Intraocular lenses sometimes becomedecentered. Distant and near vision with this zone of focus lens willnot be affected by decenteration.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects of the present invention and many of the attendantadvantages of the present invention will be readily appreciated as thesame becomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, in which like reference numerals designate like partsthroughout the figures thereof and wherein:

FIG. 1 illustrates a plan view of a multiple element zone of focushydrogel lens according to the invention;

FIG. 2 illustrates a cross-section of the multiple element zone of focushydrogel lens taken along line 22 of FIG. 1;

FIGS. 3A and 3B illustrates a schematic isometric view of an opticalsystem in which the zone of focus hydrogel lens develops images for eachlike lens element;

FIG. 4 illustrates a cross-sectional view of an embodiment in which thehydrogel lens elements of the segmented zone of focus lens are roundtaken along line 4--4 of FIG. 1;

FIG. 5 illustrates a plan view of an embodiment of the multiple elementzone of focus hydrogel lens having rectangular lens elements;

FIG. 6 illustrates a plan view of an embodiment of the multiple elementzone of focus hydrogel lens having a combination of round and pie-shapedlens elements;

FIG. 7 illustrates a plan view of an embodiment of the multiple elementzone of focus hydrogel lens having horizontal divisions between the lenselements;

FIG. 8 illustrates a plan view of an embodiment of the multiple elementzone of focus hydrogel lens having vertical divisions between the lenselements;

FIG. 9 illustrates a plan view of an embodiment of the multiple elementzone of focus hydrogel lens having both horizontal and verticaldivisions between the lens elements with the horizontal lens elementdominating;

FIG. 10 illustrates a plan view of an embodiment of the multiple elementzone of focus hydrogel lens having both horizontal and verticaldivisions between the lens elements with the vertical elementdominating;

FIG. 11 illustrates a sectional view taken across a junction between thehydrogel lens elements to show the anti-reflective coating and maskingmaterial; and,

FIG. 12 illustrates a plan view of paired hydrogel lenses for use in theleft and right eyes of a patient.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a plan view of a multiple element zone of focusimplantable lens 10, of hydrogel material, which includes an optic 12, aconvex anterior surface 14, a posterior surface 16, an edge 18therebetween, open loop haptics 20 and 22 for fixation of the lens tothe interior of the eye and positioning holes 24 and 26. Haptics 20 and22 secure into holes 24, 28 and 30 by known processes. The shape of lens10 may be varied to accommodate optical or other requirements. The lens10 is primarily illustrated as a plano convex lens, but can assume anyother convenient shape, such as meniscus, biconvex, or any other desiredlens shape. Lens 10 has a plurality of lens elements 32a-32g containedin the lens body 34. Each of the elements 32a-32g have a distinct focallength or power so as to bring objects of differing distance into focusin a common focal plane. In general, it will be found that two or threepowers will be optimum in terms of performance within the human eye. Agreater number of powers may not provide adequate sharp images forconsideration by the brain, and may unduly complicate the process ofadaption by the patient. With two different powers, the lenses of likepower can be positioned to be interspersed with lenses of the otherpower. Alternatively, lenses of like power may be located in the regionswhere adaptation is facilitated. Further alternatives include locatingthe lenses in accordance with physical characteristics of the eye itselfto accommodate retinal or corneal defects. While seven lens elements areshown in the embodiment of FIG. 1, it will be appreciated that theinvention is not so limited, and either a greater or smaller number oflens elements is permissible. The power of the individual lens elements32a-32g is determined by their radius of curvature and the index ofrefraction, either of which may be varied to provide the desired power.In the embodiment of FIG. 1, the radius of curvature for lens elements32a-32g are the same and the index of refraction of the hydrogelmaterial is varied to provide the necessary difference in power. Theindex of refraction can be modified by changing the length of thepolymer and water content while maintaining compatibility with the othercharacteristics, or by the introduction of suitable additives.Fabrication of the lens 10 may begin with the creation of a compositerod or similar structure in which the cross-section of the rod resemblesthe plan view of FIG. 1. Such a rod can be made by simultaneousextrusion of the lens elements from differing hydrogel material or byindividual extrusion or other shaping and subsequent joining of the lenselements. While the extrusion process has certain advantages,particularly that of low cost, the individual fabrication of the lenselements and subsequent joining affords the opportunity to mask thejunction with an anti-reflective coating. In either case, the resultingblank may be sliced and fabricated into lenses either by further moldingin a die which has the radii of curvature for the desired opticalcharacteristics, by conventional lathe cutting, or other similar opticalfinishing techniques.

FIG. 2 illustrates a cross-sectional view taken along line 2--2 of FIG.1 where all numerals correspond to those elements previously described.

FIGS. 3A and 3B are schematic illustrations of an optical systemutilizing the lens of FIG. 1 which incorporates two illustrations forthe purpose of clarity, and where all numerals correspond to thoseelements previously described. The hydrogel lens 10 has a plurality oflens elements 32a-32g. The lens elements 32b, 32d and 32f have a commonpower D1 and bring a far object 36 located at a far distance 38 to focuson a focal area 40, and is shown as image 36a which lies on retinalfocal plane 42 as indicated by an x-y axis at a far focal distance 44,which terminates at the retinal focal plane 42. In FIG. 3 the elements32c, 32e and 32g have a common power D2 and bring a near object 46,located at a near distance 48 to a focus in focal area 50 at a nearfocal distance 52 also terminating at the retinal focal plane 42. Thelens element 32a can have a third power D3 or can have a power D1 or D2.It can be seen that the lens elements 32b, 32d and 32f of lens 10 eachproduce an image 36a in the focal plane on a focal area 40. Similarly,elements 32c, 32e and 32g produce an image 46a on a common focal area 50which is separate and distinct from the focal area 40. Lens element 32amay have a unique power and develop an image in a unique third area, notshown for sake of clarity and brevity, or may have a power and opticalorientation to produce a sharp image of far object 36 in the focal area40 of the retinal focal plane 42, or a power and optical orientation toproduce a sharp image of near object 46 in the focal area 50 of theretinal focal plane 42.

It will be appreciated that the lens elements 32b, 32d and 32f, inaddition to producing a sharp image of far object 36, will also producean out-of-focus image of near object 46. Similarly, the lens elements32c, 32e and 32f will simultaneously produce a sharp image of nearobject 46 and an out-of-focus image of far object 36. The adaptive powerof the brain effectively rejects the out-of-focus image and permits thein-focus image of the desired object to predominate. The adaptivecapability varies with individuals and can sometimes be enhanced byselective positioning of the segments in accordance with personalcharacteristics of the individual.

FIGS. 3A, 3B and 5 have the advantage of allowing for both distant andnear even if lens is decentered.

FIG. 4 illustrates a cross-sectional embodiment of a hydrogel lens 60including an optic 62 which includes a convex anterior surface 64, aplanar posterior surface 66, an edge 68 therebetween, and a plurality oflens elements 70a-70g where the lens elements 70a-70g are round andaffix within a lens body 72 with a suitable adhesive or other materialfor molding them as an integral part of lens body 72. The plan view ofthe hydrogel lens 60 is the same as for the hydrogel lens 10 in FIG. 1where the plurality of lens elements 32a-32g correspond in overhead planview to the corresponding lens elements of this FIG. in which thealphabetic letters correspond such as 70a being equivalent to 32a and soforth. The differing powers are provided by fabricating the lenselements with different radii of curvature. Since the segments do nothave a uniform curvature, conventional grind or lathe cutting techniquesare not generally adequate for fabrication where the lens elements arean integral assembly with the lens body 72. Where the integral structureis desired, it may be desirable to form the lens in a die havingsuitable dimensions or, as previously described, individually fabricatethe lens elements and join them after the curved surface is fabricated.

FIG. 5 illustrates an embodiment of the zone of a focus hydrogel lens80, including an optic 82, in which the lens elements 98a-98u aregenerally rectangular in shape and having a uniform radius of curvature,including a convex anterior top surface 84, a plano posterior surface86, an edge 88 therebetween, and positioning holes 90-92 and haptics94-95 engaged in holes 96-97. A structure such as this can be fabricatedby extrusion, using compatible hydrogel materials which have differentindices of refraction. Alternatively, a composite structure can be madeby assembling rectangular rods, having different indices of refraction,into a unitary assembly and slicing blanks therefrom. The blanks can beprocessed into lenses with conventional techniques. The rods can beaffixed to each other with suitable adhesive.

In addition to having different indices of refraction, the individualelements can be made of different colors. The individual lens elements98a, 98c, 98e, 98g, 98i, 98k, 98m, 98o, 98q and 98s have like powers;bring incident rays to focus on a common area; and are colored red orsome other suitable color. Lens elements 98b, 98d, 98f, 98h, 98j, 98l,98n, 98p, 98r and 98t have like powers, differing from the common powerof the other group of elements; bring incident rays to a focus on acommon area distinct from the area of the other group of elements; andare of a different suitable color such as blue. Thus, colors areassigned to specific lens powers to assist the brain in distinguishingthe images produced from the two groups of elements.

FIG. 6 illustrates an embodiment of a hydrogel lens 100, including anoptic 102, a convex anterior surface 104, a plan surface 106, an edge108 therebetween, and positioning holes 110 and 112 and haptics 114 and116 engaged in holes 118 and 120. An optic 102 includes a cylindricalcentral lens element 122 and a plurality of peripherally located radiallens elements 124a-124f about the central lens element 122. The lenselements 122 and 124a-124f may be various powers and colors having thelens elements with common powers of the same color. The lens elementswith common powers are optically aligned to produce an image on a commonarea of the retina.

FIG. 7 illustrates an embodiment of a hydrogel lens 130 including anoptic 132, a convex anterior surface 134, a plano surface 136, edge 138therebetween, and positioning holes 140-142 and haptics 144-146 engagedin holes 148-150. The hydrogel lens optic 132 is made up of lenselements 150a-150c which are joined along the corresponding horizontalaxis between the lens elements 150a-150c. In the case where threedifferent powers are used for the three lens elements 150a-150c, theelements may be optically aligned to produce an image on the retina inthe area corresponding roughly to the geometry of the lens 130. Thehaptics 144 and 146 will be located to provide the optimum ease ofadaptation. For some persons, the optimum position for the most commonlyused image brought to a focus by lens element 150a, will be thehorizontal central portion of the retina. If this is the case, thehaptics 144 and 146 will be located to place lens element 150a in aposition to bring its image to the central portion of the retina.

FIG. 8 illustrates a three-element embodiment of a hydrogel lens 160similar to that of FIG. 7 with the haptics arranged to place the centralelement in the vertical orientation. The lens 160 includes an optic 162,convex anterior surface 164, posterior surface 166, an edge 168therebetween, and positioning holes 170-172 and haptics 174 and 176engaged in holes 178 and 180. The optic 162 includes lens elements182a-182c joined along the corresponding axis between the lens elements182a-182c. The lens elements of FIGS. 7 and 8 can be colored blue, redor yellow or be transparent. The lens elements can be of the same ordifferent powers, but it is desirable that like powers share a commonarea of the retina.

FIG. 9 illustrates a geometric arrangement in which the horizontalcentral element has substantially more area than the other elements. Thehydrogel lens includes an optic 192, a convex anterior surface 194, aplano posterior surface 196, an edge 198 therebetween, and positioningholes 200 and 202 and haptics 204 and 206 engaged in holes 208 and 210.The optic 192 includes a horizontally aligned lens element 2, verticallyaligned lens element portions 214a and 214b perpendicular to thehorizontally aligned lens element 212 in a lens body 216 includingportions 216a-216d. This geometrical configuration may employcombinations of differing powers and colors as previously described.

FIG. 1O illustrates an arrangement comparable to that of FIG. 9, butwith the central lens element arranged in the vertical plane. Thehydrogel lens 220 includes an optic 222, a convex anterior surface 224,a plano surface 226, an edge 228 therebetween, and positioning holes 230and 232 and haptic 234 and 236 engaged in holes 238 and 240. The optic222 includes a vertically aligned lens element 242, horizontally alignedlens elements 244a-244n perpendicular to the vertically aligned lenselement 242 in a lens body 246 including portions 246a-246d. Thisgeometrical configuration may employ combinations of differing powersand colors as previously described.

FIG. 11 illustrates a cross-sectional view at the junction 250 betweenhydrogel elements joined with adhesive or other suitable material takenalong line 11--11 of FIG. 1. A hydrogel lens element 32a is joined to ahydrogel lens element 32c with a suitable adhesive material 254. Anopaque layer 256 of highly pigmented material may be added to reducereflection caused by the junction between the elements. The adhesivematerial 254 may contain an anti-reflection material or such materialmay be applied directly to the abutting surfaces.

FIG. 12 illustrates two hydrogel lenses 260 and 262 for the right andleft eye, respectively, having lens elements of comparable power andcolor arranged in the same geometric position in each lens. For example,lens element 264a for the left eye, has the same power and color as thelens element 266a for the right eye. In this embodiment, the lenselements 264a-264c for the left eye have powers respectivelycorresponding to the powers of lens elements 266a-266c for the righteye. This too, is to facilitate the adaptation process.

MODE OF OPERATION

Reduction of the cost of the lenses would have the effect of increasingthe availability of this procedure to those who currently lack theeconomic means to afford such an operation. This is particularly thecase in third world countries where costs are often the overridingconsideration in medical care.

There is no question that the technique of using less than the entireretina is usually not as desirable as a system which duplicates thenormal lens use of the entire retina. There is a loss of acuity whichshows up in reduced resolution and contrast, particularly in low lightconditions. In addition, the accommodation of the brain to such a systemtakes a period of time, and the degree of success in such accommodationvaries with individuals.

In the case where a defective natural lens is to be replaced, it iscustomary to make extensive measurements on the eye prior to the removalof the defective natural lens and its replacement with a fixed focusimplantable lens. Such measurements allow the selection of a lens havingappropriate power for the individual, and the nominal distance to theobject which is desired to be brought into focus on the retina. Thisapproach to the problem has the disadvantage that a wide range of powersmust be available to the surgeon. Since each lens is individuallyfabricated, the economic burden of fabricating a wide variety of powersadds substantially to the cost of lenses. It would be much cheaper tomanufacture only a few lenses and use them in all patients. The cost ofmanufacture would be reduced and inventory requirements would be muchless burdensome.

The flexible hydrogel material allows the lens to be folded or rolled upand inserted into the eye through an incision or puncture which is muchsmaller than required for a conventional, rigid lens. Since theinsertion procedure is simplified, the cost of implantation is reduced.

Various modifications can be made to the present invention withoutdeparting from the apparent scope thereof.

I claim:
 1. A zone of focus hydrogel lens for use with an eyecomprising:a. a plurality of hydrogel lens elements joined to form aunitary lens structure having a front surface, a rear surface and acircular periphery; b. each of said hydrogel lens elements serving tocreate an image on a distinct portion of the retina; and, c. at leasttwo of said hydrogel lens elements having different powers wherebyobjects at different distances from the eye are simultaneously broughtto a focus on distinct portions of the retina; and, d. at least two ofsaid lens elements are of different colors.
 2. A lens according to claim1 wherein said lens elements are round.
 3. A lens according to claim 2wherein at least two of said lens elements are of hydrogel materialshaving different indices of refraction.
 4. A lens according to claim 1comprised of lens elements each having different indices of refraction.5. A lens according to claim 4 consisting of three lens elements.
 6. Alens according to claim 5 having a horizontally oriented lens elementlarger than said other lens elements.
 7. A lens according to claim 5having a vertically oriented lens element larger than said other lenselements.
 8. A lens according to claim 5 wherein said lens elements arehorizontally oriented.
 9. A lens according to claim 5 wherein said lenselements are vertically oriented.
 10. A lens according to claim 3wherein the junctions between lens elements includes an anti-reflectivecoating.
 11. First and second lenses according to claim 1 for use inleft and right eyes wherein like power elements ar similarly positioned.